A wide variety of different mechanical devices have been developed in order to apply force between two objects or to position one object relative to another. For example, numerous types of jacks are known in the art, and numerous types of robotic arms have been developed for particular applications in industry.
With respect to mechanical jacks, it is well known that jacks can be used to elevate one object relative to another or to apply a force between two objects. Mechanical jacks typically come in three types: lever operated jacks, screw operated jacks and hydraulic jacks. A lever jack uses the principle of a small force over a large distance to elevate a heavy load over a small distance. Ratchets are often provided so the mechanical advantage of the lever may be sequentially applied to elevate the load a desired amount within the jacks throw distance. Screw jacks on the other hand, gain a mechanical advantage by use of a thread wherein rotary movement advances the screw to move the load. Hydraulic jacks implement the advantage of a pressurized fluid to move an extendable support member.
Robotic arms are known to incorporate a variety of mechanisms. For example, some robotic arms merely pivot about an axis so that a distal end of the arm moves from one location to another to accomplish a desired task. It is known to construct arms that employ a scissor action so that the arm may move between A collapsed state and an extended state. Some arms may use telescoping pieces to move between extended and contracted states. Other robotic arms may use an lever action wherein one end of the lever is mechanically driven so as to manipulate the opposite lever end.
One industry that employs a variety of different force applying structures is the recreational vehicle industry. For example, it is known the recreational vehicle industry to use mechanical jacks to raise and lower the tongue of a trailer. It is also known to use mechanical jacks at various locations on the undercarriage of the vehicle so as to stabilize and/or level the vehicle when it is parked. Typical jacks used in this application include all three types discussed above. It is also known to provide recreational vehicles with sliding compartments to increase the useable space within the vehicle when it is to be inhabited.
Despite the existence of various mechanical arms and mechanical jacks, there remains a need for improved mechanical arms which may function either to apply force between two objects or to position one object with respect to another. A need exists for simplified, reliable mechanical arms that can serve these needs. There is further need for such mechanical arms that have a high strength to weight ratio. A further need exists for such mechanical arms to collapse within a small dimension yet expand over a significant range. The present invention is directed to meeting these needs.